AB1365 PROPOSAL FOR A STANDARDIZED ULTRASOUND SCANNING PROTOCOL OF THE NAIL PLATE.
Authors: D. Rotta, G. Adami, F. Bellinato, A. Fassio, L. Idolazzi, P. Gisondi, F. Tozzi, E. Filippucci, M. Rossini
Journal: Annals of the Rheumatic Diseases (2022)

Background Ultrasonography of the nails with high frequency linear transducers can properly perform morphological images, achieving highly descriptive power but the lack of standardization may hesitate in lack of reproducibility and scarce usefulness. Objectives The aim of this study was to provide a detailed scan protocol of nail plate, including comparison of scan planes and probe positioning. Methods Transversal and longitudinal ultrasound scans were performed on each fingernail of both hands in healthy subjects. Nail plate thickness and Power Doppler of the nail bed were recorded. All the images were acquired using Canon Aplio i800 with a linear transducer of 22 MHz (i22LHB). Two different operators performed evaluation of thickness at distal, middle and proximal portion of nail in longitudinal view and at 0°, -45° and +45° for transverse view (Figure 1). ANOVA for repeated measures was used to determine differences between nail of the different digits. Figure 1. Longitudinal and transverse view of the nail. In yellow the position and angles of the caliper used for acquiring the measures Results The study sample was composed of 27 healthy subjects between 25- and 40- year old with no rheumatological or dermatological nail issues. A total of 270 nails were scanned; none of them was excluded due to comorbidity, trauma or other conditions which can interfere in the evaluation. A decrease in nail thickness was observed from first to fifth digit, regardless the hand (dominant or not), that resulted significant for the ANOVA. No differences were found regarding the thickness in the different segments of nail plate and this occurred both for longitudinal and transverse scans. Conclusion We demonstrated the absence of a statistically significant difference between thickness at proximal, middle and distal portion of the nail in longitudinal view or at any different angle in transverse view, concluding the fastest and easiest way to measure the nail plate thickness is in the longitudinal view at the middle segment, avoiding potential issues in positioning the probe in the transverse view or in positioning the caliper at proximal or distal segment in longitudinal view. All the nails should be scanned per protocol, since the thickness is variable and the fifth may be the most interesting in order to consider its highest variance. References [1]Fassio A. et al.; Clin Rheumatol. 2020 May;39(5):1391-1404. doi: 10.1007/s10067-019-04748-2. Epub 2019 Aug 22. Table 1. ANOVA for repeated measures of the nail plate thickness. A trend in decreasing P value is clearly visible from first to fifth. P considered statistically significant when ≤ 0.05 LONGITUDINAL TRANSVERSE PROXIMAL -45° Row-mean 1 2 3 4 Row-mean 1 2 3 4 2 1.000 2 0.731 3 0.765 1.000 3 0.264 1.000 4 0.028 0.888 1.000 4 0.000 0.056 0.187 5 0.000 0.001 0.003 0.158 5 0.000 0.005 0.023 1.000 MIDDLE 0° Row-mean 1 2 3 4 Row-mean 1 2 3 4 2 1.000 2 0.719 3 1.000 1.000 3 0.056 1.000 4 0.070 1.000 1.000 4 0.000 0.158 1.000 5 0.000 0.001 0.002 0.095 5 0.000 0.025 0.389 1.000 DISTAL +45° Row-mean 1 2 3 4 Row-mean 1 2 3 4 2 1.000 2 1.000 3 0.854 1.000 3 0.765 1.000 4 0.006 0.093 0.754 4 0.050 0.583 1.000 5 0.000 0.000 0.000 0.114 5 0.000 0.001 0.016 0.323 Disclosure of Interests None declared